Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/721

Rh dangerous antagonist to animals much larger than itself, and occasionally even to man. The rutting season occurs in March, and the female, secure in her burrow, produces her young—four or ﬁve at a birth—in June or July. In de- fence of these she is exceedingly bold, and the Indians, according to Cowes, “have been heard to say that they would sooner encounter a she-bear with her cubs than a carcajou (the Indian name of the glutton) under the same circumstances.” The wolverene has a curious habit which has not hitherto been observed in any other of the lower animals. On catching sight of its relentless human enemy, it may be observed, before ﬁnally determining on ﬂight, sitting on its haunches, and, in order to get a clearer view of the danger, shading its eyes with one of its forepaws. When pressed for food it becomes fearless, and has then been known to come on board an ice-bound vessel, and in pre- sence of the crew to seize on a canister of meat. The flesh of the glutton is uneatable; it is therefore only valuable for its fur, which, when several skins are sewn together, forms elegant hearth and carriage rugs.  {{ti|1em|{{larger|GLYCAS}}, {{sc|Michael}}, a Byzantine historian, often called Siculus. The time when he ﬂourished is very uncertain. He is justly reckoned among the better Byzantine historians on account of the terseness and perspicuity of his style. His MS. letters still extant are addressed to the last Constan- tine ; their authenticity, however, has been questioned. His chief work is BL’BAog xpowm}, divided into four parts, treating of history from the creation of the world to the death of Alexis I. Conmenus. The best edition is that by J. Bekker, in the Bonn collection of the Byzantines (183G).}}  GLYCERIN,, or (in pharmacy ), a sugar-like substance obtainable from most natural fatty bodies by the action of alkalies and similar reagents, whereby the fats are decomposed, water being taken up, and glycerin being formed together with the alkaline salt of some particular acid (varying with the nature of the fat). Owing to their possession of this common property, these natural fatty bodies and Various artiﬁcial derivatives of glycerin, which behave in the same way when treated with alkalies, are known as glycerides. This decomposition into an organic acid and a substance of more or less neutral character is a typical kind of reaction with numerous classes of organic bodies, and is termed saponi— jication, from the circumstance that the ordinary process of soap-making consists simply in the formation from natural fatty bodies and alkalies of the alkaline salts of the fatty acids thence derivable, soap being a mixture of these alkaline salts in various proportions, according to the particular pur- poses for which it is required, and its price. In the ordinary process of soap-making the complementary product, glycerin, remains dissolved in the aqueous liquors from which the soap is separated, and is usually thrown away; in many other instances, however, in which a substance capable of undergoing a reaction of saponification is thus treated, the product complementary to the alkaline salt is the more im- portant of the two. The fact that soap is obtainable by boiling together oily or fatty substances and alkalies (such as potashes and natron or mineral alkali) was known at an early period of history, being mentioned by Pliny, Galen, Aetius, and Paulus ngineta. On the other hand, substances referred to in the Old Testament and translated “ soap ” (0.9., Jeremiah ii. 2'3, “ For though thou wash thee with nitre [properly. natron], aud take thee much soap ;” Malachi iii. 2, “For he is like a refiner’s ﬁre, and like fuller’s soap”) refer to the alkali itself (viz., boritlt=vegetable alkali, potash; or aeter: mineral alkali, soda), and not to the substances prepared from oily bodies and these alkaline matters. Similarly Homer makes no mention of' soap whilst describing the laundry operations of Nausicaa. The discovery of glycerin, however, is of modern origin, the body having been ﬁrst described in 1776 by Scheele under the name of oelsiiss (principe doux des huiles—sweet principle of oils), and more fully investigated subsequently by Chevreul, Berthelot, and many other chemists, from whose researches it results that glycerin is a trihydric alcohol indicated by the formula C3H5(OH)3, the natural fats and oils, and the glycerides generally, being substances of the nature of compound ethers formed from glycerin by the replacement of the hydrogen of the OH groups by the radicals of certain acids, called for that reason “fatty acids.” The relationship of these glycerides to glycerin will be more conveniently shown by an example, such as the series of bodies formed from glycerin by replacement of hydrogen by “stearyl” (CISH3SO), the radical of stearic acid (ClsH35O.OH):—

Glycerin. Monostcarin. Distem'in. Tristearin.

CIH... . 0H CH2. 0(ClstlgsO) CU,. 0(C15H350) CH,. 0(01311350) (i‘II . 011 CI“ . OH CH . 0(CﬂlInO) CII . 0(C1311350) ClI._. . OII C112 . 011 0112 . OII C112 . 0(C“,II;,50)

These four substances evidently form a progressive series, each number of which differs from the preceding one in the same way, viz., that one more stearyl group replaces hydrogen in the original OH groups. The process of saponiﬁcation may be viewed as the gradual progressive transformation of tristearin, or some analogous] y constituted substance, into distearin, monostearin, and glycerin, or as the similar transformation of a substance analogous to distearin or to monostearin into glycerin. If the reaction is brought about in presence of an alkali, the acid set free becomes transformed into the corresponding alkaline salt; but if the decomposition is effected without the presence of an alkali (i.e., by means of water alone, or by an acid ﬂuid), the acid set free and the glycerin are ob- tained together in a form which usually admits of their ready separation. It is noticeable that with few exceptions the fatty and oily matters occurring in nature are sub— stances analogous to tristearin, i.e., they are trebly replaced glycerins. Amongst these glycerides may be mentioned the following:—

Tristcarz'n—C;,H5(O.C‘18H350)3. The chief constituent of hard animal fats, such as beef and mutton tallow, &C.; also con- tained in many vegetable fats in smaller quantity.

Triolcin—03H5(0.01811330)? Largely present in olive oil and other saponiﬁable vegetable oils and soft fats; also present in animal fats, especially hog’s lard.

Trz'palmiti'n—C3H5(O.(31611310)? The chief constituent of palm oil; also contained in greater or less quantities in human fat, olive oil, and other animal and vegetable fats.

Tri-ricinclci)z—-C3H5(O.(‘18113302)3. The main constituent of castor oil.

Other analogous glycerides are apparently contained in greater or smaller quantity in certain other oils. Thus in cows’ butter, tributyrz'n, 03H5(O.C,HTO)3, and the analogous glycerides of other readily volatile acids closely resembling butyric acid, are present in. small quantity ; the production of these acids on saponiﬁcatiOn and distillation with dilute sulphuric acid is utilized as a test of a purity of butter as sold. Triucetin, 03H5(O.C_3H3O)3, is appar- ently contained in cod-liver oil. Sonie other glycerides isolated from natural sources are analogous in composi- tion to tristearin, but with this difference, that the three radicals which replace hydrogen in glycerin are not all identical ; thus kephalin, myelin, and lecithin are glycerides in which two hydrogens are replaced by fatty acid radicals, and the third by a complex phosphoric acid derivative. .In no case, however, is the existence of a natural glycerlde